1. Field of the Invention
This invention relates to a material gathering device for a mining machine and more particularly to a pair of counter-rotating gathering discs mounted on a gathering platform and having a plurality of arm members extending through radially positioned slots in each disc and supported to move upwardly and downwardly within the slots to permit the arms to pass beneath a material guide upon each revolution of the disc.
2. Description of the Prior Art
It is the conventional practice to utilize a material gathering device with a continuous mining machine in underground mining operations. The gathering device includes a gathering platform that extends transversely across the front of the machine and rearwardly toward the receiving end portion of an endless conveyor. The conveyor extends longitudinally along the center line of the mining machine for transporting mined material rearwardly from the gathering platform to a discharge end portion of the conveyor. A rotatable mining head, such as a driven cutter drum illustrated in U.S. Pat. Nos. 3,712,678 and 3,774,969, is rotatably mounted transversely by pivotal boom arms to the front end of the mining machine. The mining head extends forwardly of the material gathering device.
By operation of hydraulically controlled piston cylinder assemblies the boom pivots upwardly and downwardly about an axis transverse to the longitudinal axis of the mining machine. With this arrangement the mining head makes upward and downward shear cuts in the mine face. The material gathering device gathers the dislodged material as the mining machine advances forwardly, and the rotating discs feed the dislodged material rearwardly onto the receiving end portion of the conveyor. The conveyor then transports the dislodged material rearwardly to the discharge end portion for loading into a suitable haulage vehicle.
U.S. Pat. Nos. 4,056,189; 3,817,579 and 3,417,851 disclose counter-rotating discs positioned forwardly and on opposite sides of the receiving end portion of the conveyor on the gathering platform. The rotatably driven discs convey the dislodged material rearwardly from the front end portion of the gathering platform onto the receiving end of the conveyor as the mining machine advances. U.S. Pat. No. 3,417,851 utilizes wings that extend forwardly from the sidewalls of the conveyor into overlying relation with the rotatable discs. The wings include strippers that extend forwardly to the centers of the gathering discs where the end portions of the strippers are supported by bearings at the axes of rotation of the gathering discs. With this arrangement the wings and their associated strippers form a continuation of the sidewalls of the conveyor so that the mined material moved inwardly toward the center of the gathering platform by the counter-rotating discs is directed from the discs onto the receiving end of the conveyor chain.
The gathering discs of U.S. Pat. No. 2,575,287 include a plurality of equally spaced gathering arms that project radially from each disc. The arms are carried by the rotating discs and serve to directly feed the mined material collected on the gathering platform onto a conveyor extending longitudinally between the discs.
The material gathering device of U.S. Pat. No. 3,328,087 includes a pair of triple-armed feed wheels that rotate about parallel vertical axes positioned on opposite sides of the conveyor to direct the dislodged material onto the receiving end of the conveyor. U.S. Pat. Nos. 2,730,344 and 3,620,345 disclose gathering arms secured to an endless chain that are guided for orbital movement on the surface of the gathering platform or the gathering discs. The arm members are operable upon rotation of the chains to move the mined material deposited on the gathering platform onto the receiving end portion of the conveyor.
U.S. Pat. No. 3,817,579 discloses a plurality of upstanding vanes that extend in a curved path outwardly from the center to the periphery of each disc. The vanes are rotated by the disc beneath a fence that is positioned above the disc and extends from the forward end of the conveyor sidewalls to the axis of rotation of the disc. Upon rotation of the disc each vane is operable to guide the dislodged material toward the fence and to move the mined material into contact with the fence so that the material is swept centrally and rearwardly on the platform onto the receiving end of the conveyor.
Further, a problem is encountered with gathering discs of the type described above, particularly with plain discs having ribs or vanes of a relatively short vertical height in conveying wet and sloppy material and/or large pieces of mined material. The height of the ribs or vanes is limited by the clearance available between the lower surface of the material guide or fence and the upper surface of the disc for the ribs to pass beneath the lower surface of the material guide. The clearance is maintained at a minimum so that substantially all the dislodged material is moved into contact with the material guide and doesn't pass beneath the material guide. By positioning the material guide lower face as close as possible to the upper surface of the disc substantially all the mined material is swept from the disc onto the conveyor.
Therefore, there is need for a mining machine material gathering apparatus that is operable to efficiently sweep the gathering platform of mined material and particularly wet and sloppy material and/or large pieces of mined material by ribs or vanes having a vertical height operable to sweep the material toward the material guide. However, the vanes must be operable to rotate with the respective discs beneath the material guide where the guide is positioned as close as possible to the upper surfaces of the discs so that the mined material is swept from discs onto the conveyor.